Pumping apparatus



May 26, 1936. R. E. LAMBERTON 2,041,717

PUMPING APPARATUS Filed NOV. 27, 1954 Patented May 26, 1936' UNITEDSTATES PATENT OFFICE PUDIPING APPARATUS Application November 27, 1934,Serial No. 755,014 13 Claims. (01. 2so -2s'),

My invention relates to pumping apparatus for compressible fluids, and,from another aspect, to improved unloading means for such pumpingapparatus.

When a multi-stage compressor is provided with a total closure intakeunloader for the low pressure cylinder and unloads the high pressurecylinder by opening and maintaining open the inlet valves of the latter,there is a tendency for the intercooler pressure gradually to build up,due to leakage past the intake unloader valve and absence of removal ofair from the intercoolerby the high pressure cylinder; and thereforethere is a periodic popping of the safety valve which is provided on theintercooler, which is annoying and at times undesirable. If, however,means can be provided for venting the intercooler at such a rate that amoderate pressure may still be maintained therein, while avoiding thebuilding up of an excessive pressure, this would be desirable; and fromone aspect my invention consists in the provision of improved meansforaccomplishing this function.

An object of my invention is to provide an improved pumping apparatus.Another object of my invention is to provide an improved multi stagepumping apparatus having improved unloading means. Still another objectof my invention is to provide an improved arrangement for maintainingintercooler pressure within desired limits during the unloaded operationof a multistage compressor. Yet another object of my invention is toprovide an improved automatically- Fig. 1 is a side elevational view ofa multistage compressor arranged in accordance with the illustrativeembodiment of my invention;

Fig. 2 is a vertical section taken on line 2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view through a portion of a highpressure cylinder unloading means; and

Fig. is a horizontal section showing details of construction of theintake type unloader casing.

From the drawing it will be noted-that the compound compressor l shownhas a frame 2, a drive shaft 3, a flywheel 4 driven by suitable drivingconnections, including herein a belt 5 of which a portion only is shown,the crankshaft 3 serving to actuate the pistons (not shown) in the lowpressure cylinder 6 and in the high pressure cylinder I. The lowpressure cylinder 6 discharges through a connection 8 to an intercooler9 provided with a suitable pop valve l8; and from the intercooler thecooled and partially coinpressed fluid passes through a connection H tothe high pressure cylinder 1, after a further compression in which it isdischarged through a discharge line l2 to any suitable point of use.

' The low pressure cylinder 6 receives air through 22 adapted to closethe opening through the 20 web l9 and a portion 23 adapted to close theopening through the web 20 is reciprocable in the casing l-i. Valve 2|is normally held in open position by a spring 24 acting upon its lowerend,

and may be moved to closed position by a plunger 25 25 reciprocable in acylinder 26 and adapted to be supplied with air through a connection 21under the control of a pilot valve 28 supplied with pressure from thehigh pressure discharge line 12 through a connection. When the pres- 30sure in the compressor discharge line l2 reaches a predetermined desiredmaximum, the pilot valve 28 operates in a well-known manner to supplyfluid through the line 29 and the connection 21 to the space above thepiston 25, and thereby 35 as a pump, due to the maintaining open or its45 inlet valves 32, and is also unloaded, and accordingly there will beno fluid discharged from the intercooler 9 by the high pressure cylinderI; and indeed, should the discharge valves of the high pressure cylinderprove at all leaky, there may be- 50 some return of air from the line I2to the intercooler. Moreover, in theevent that air leaks pastAccordingly, 40

may? build up sufliciently to open the pop valve, with undesirable noiseand with some waste of power, and undesirable heating dueto thecompression of the air to a higher pressure than is desired in theintercooler.

To avoid the difficulties mentioned I have provided in alignment withthe cylinder 26 and mounted within a cover 34 for that cylinder, an

automatic arrangement for venting, as desired, the intercooler. The head34 contains a pair of alined cylindrical chambers 35 and 36 connected bya passage of reduced cross-section 31 whose opposite ends are surroundedby conical seats respectively numbered 38 and 39. The central passage 31is communicable through a lateral passage 40 controlled by an adjustableneedle valve 4| with a. passage 42 which opens into the space IB'withinthe intake closure valve casing l4, and accordingly any noise from airflowing outward through the passage 42 will be muflied by the aircleaner Within the chambers 35 and 36 there are arranged respectively anend seating valve 44 and a plunger 45, each of which has astem-extending towards the other, which stems are respectively numbered46 and 41, and which are of such length that the valve and plunger, eachof which is beveled to cooperate with one of the conical seats, can notboth seat at the same time. A spring 48 normally maintains valve 44seated and plunger 45 oil of seat 39. The valve 44 is provided with alongitudinal groove 53 so that when it is unseated fluid may flowlongitudinally along it. The chamber 49 above the valve 44 is connectedby a connection 50 with any suitable point between the low pressurecylinder discharge valves and the high pressure cylinder inlet valves,herein to the discharge line 8 from the low pressure cylinder. A passage5| formed in a threaded plug 52 which limits the downward movement oftheplunger 45, subjects thelower end of the latter continuously to thepressure conditions to which the piston 25 is subjected. Accordinglywhenever fluid is supplied to depress the piston 25, fluid also flowsthrough the passage 5| to raise the plunger 45, and because the pressurebelow the plunger 45 is higher than the pressure above the valve 44, thelatter is unseated, and

communication is established between passage 59 and passage 42. Thevalve 4| is preferably adjusted in such manner as to maintain a pressurein the intercooler suited to the design of the compressor, the pressureranging from 30 lbs. in compressors having a relatively low overallrange of compression to considerably higher pressures as the highpressure discharge pressure rises. Piston 25 and cylinder 23, and piston45 and cylinder 36 will be noted to constitute alined, reversely actingservo motors having communicating cylinders.

The mode of operation of the invention will be very readily understoodfrom what has been already said. When the compressor discharge pressurerises to the desired maximum value, the

pressure conducted through the line 29 and acting upon the pilotmechanism 28 causes the latter to admit pressure simultaneously to closethe valve 2| and to open the inlet valves- 32. The compressor istherefore unloaded and while pressure might tend to build up in theintercooler due to leakage, as previously explained, there will be nopressure discharged from the intercooler by the high pressure cylinder.The pressure in the intercooler will, however, be prevented frombuilding up to too high a value, because as the plunger 25 closes thevalve 2|, the plunger 45 simultaneously will unseat the valve 44; and aleak connection will thus be opened from the line 8 which communicateswith the interior of the intercooler, the air from the latter ventingthrough the passage 50, chamber 49, through the groove 53, passage 31,lateral passage 40, past the needle valve 4|, through the passage 42,into the space l6 and thus escaping to the atmosphere. The intercoolerpressure will remain substantially whatever is fixed by the setting ofthe valve 4|; and the setting of this valve will be determined, byobservation, substantially merely to ofiset the rates of fluid supplyinto the intercooler by leakage back from the line I 2, and due toleakage past the closed intake valve 2 I. When the compressor is to beloaded again due to drop in discharge line pressure, the pressure abovethe piston 25 and below the piston 45 will be simultaneously vented; andthe valve 44 will close the leak connection simultaneously with theopening of the intake closure valve 2|.

It will be evident that I have provided a very simple and efiectivearrangement for maintaining intercooler pressure at a desired valueduring normal unloaded operation of the compressor. It will be obviousthat the arrangement is capable of application to portable compressorsas well as stationary'compressors, and usable with any arrangement. ofunloading in which an intake is closed to a lower stage cylinder anddischarge from an intercooler is precluded by virtue of the type of theunloading apparatus used for the next higher pressure stage cylinder.The apparatus will be noted to be simple, efiective, adjustable todifferent conditions and wholly automatic in operation. 7

While I have in this application specifically described one form whichmy invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration, and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is 1. Incombination, a multi-stage compressor having anintercooler, an intakeclosure type unloader for the low pressurecylinder, an unloadingapparatus for the high pressure cylinder effective to interrupt thedischarge of pressure from the intercooler by said high pressurecylinder, and means for simultaneously providing a controlled venting ofthe intercooler pressure.

2. In combination, a multi-stage compressor having an intercooler, anintake closure type unloader for the low pressure cylinder, an unloadingapparatus for the high pressure cylinder effective to interrupt thedischarge of pressure from the intercooler by said high pressurecylinder, and means governed by compressor discharge pressure foreffecting operation of said unloading means, and means also governed bycompressor discharge pressure for simultaneously providing a controlledventing of the intercooler pressure, said last means and a portion ofsaid unloading.

equipment each including a valve actuating plunger, said plungersarranged coaxially.

5. In combination, a multi-stage compressor having an intercooler, anintake closure type unloader for the low pressure cylinder, an unloadingapparatus for the high pressure cylinder effective to interrupt thedischarge of pressure from the intercooler by said high pressurecylinder, means for effecting operation of said unloading means,

and means for simultaneously providing a controlled venting of theintercoolerpressure including a relief valve mounted upon said intaketype unloader and opened when the latter is closed.

6. In combination, a multi-stage compressor having an intercooler, anintake closure type unloader for the low pressure cylinder, an unloadingapparatus for the high pressure cylinder effective to interrupt thedischarge of pressure from the intercooler by said high pressurecylinder, means .;for effecting operation of said unloading means,

and means for simultaneously providing a controlled venting of theintercooler pressure including a relief valve mounted upon said intaketype unloader and moving in the same direction as the latter to efiectclosure.

7. In combination, in a multi-stage compressor, high and low pressurecylinders and an intercooler, an intake closure unloader for the lowpressure cylinder including a servo motor cylinder and piston, means forinterrupting pumping by the high pressure cylinder, and intercoolerventing means including a second servo motor cylinder and piston coaxialwith t e first-mentioned servo motor cylinder and piston.

8. In combination, in a multi-stage compressor, high and low pressurecylinders and an intercooler, an intake closure unloader for the lowpressure cylinder including a servo motor cylinder and piston, means forinterrupting pumping by the high pressure cylinder, and intercoolerventing means including a second servo motor cylinder and piston coaxialwith the first-mentioned servo motor cylinder and piston, said servomotor cylinders freely communicating with each other.

9. In combination, a multi-stage compressor having high and low pressurecylinders and means connecting the discharge of the latter to the intakeof the former, intake closure unloadin means for the low pressurecylinder, unloading means for the high pressure cylinder interruptingwhen effective the pumping action thereof, and

means for discharging fluid from said connecting means while saidunloading means are effective at at least as low a pressure as normallyprevails in said connection during pumping.

10. In combination, a multi-stage compressor having high. and lowpressure cylinders and means connecting the discharge of the latter tothe intake of the former, intake closure unloading means for the lowpressure cylinder, unloading means for the high pressure cylinderinterruptmg when effective the pumping action thereof,

and means actuated concurrently with said unloading means fordischarging fluid from said connecting means while. said unloading meansare effective.

11. In combination, a multi-stage compressor having high and lowpressure cylinders and means connecting the discharge of the latter tothe intake of the former, intake closure unloading means for the lowpressure cylinder, unloading means for the high pressure ylinderinterrupting when effective the pum ping action thereof, means fordischarging fluid from said connecting means while said unloading meansare effective, and common pilot means for said unloading and fluiddischarging means.

12. In combination, a multi-stage compressor having high and low!pressure cylinders and means connecting the discharge of the latter tothe intake of the former, intake closure unloading means for the lowpressure cylinder, unloading means for the high pressure cylinderinterrupting when efiective the pumping action thereof, means fordischarging fluid from said connecting means while said unloading meansare effective, and common controlling means governed by compressordischarge pressure for said unloading and fluid discharging means.

13.In combination, a multi-stage compressor having high and low pressurecylinders and means connecting the discharge of the latter to the intakeof the former, intake closure unloading means for the low pressurecylinder, unloading means for the high pressure cylinder interruptingwhen effective pumping action thereof, means for discharging fluid fromsaid connecting means during unloaded operation of the compressor, and apilot valve responsive to compressor discharge pressure "controllingsupply and venting of com-

